"I fundamentally disagree with her on nearly every point. But she believes this stuff. I think she's naïve but she believes it.

"People question her motives but she's just flipping strong-willed and dogmatic. I like her a lot."

Ms Mensch has similar praise for her political opponent.

"Tom Watson was the biggest surprise to me when I got into parliament," the Corby and East Northamptonshire MP said.

"I'd heard all the stories – Brown's consigliere and so forth. I thought of him as a Dark Lord of the Sith.

"Turns out he is the most likeable guy imaginable, totally straight and takes no crap from anyone."

She added: "He genuinely believes News Corp is a force for evil and he acts accordingly. I diametrically disagree with him. But [he is one of] his party's biggest talents."

Mr Watson and Ms Mensch have both had their profiles immeasurably improved by the media committee's report into phone-hacking at News of the World.

Yesterday the Commons agreed to send the report to the standards and privileges committee, to decide what should happen to the three men who misled Mr Watson, Ms Mensch and the other MPs who scrutinised phone-hacking.